The invention relates to a gear-reduction device for measuring and transmitting rotary and swivel movements. The gear-reduction device is a type of transmission with a plurality of wheel/pinion pairs, i.e., unitary elements in which a gear wheel and a pinion gear are rigidly mounted on a common gear axle. When coupled to a rotary object whose movement is to be measured, the gear-reduction device produces an output angle of rotation that is reduced in relation to the angular movement of the rotary object, whereby the measuring range is expanded.
To measure angles of rotation and numbers of revolutions, it has so far been customary to use gears of different diameters and combine them in a multi-stage gearbox with a high ratio of gear reduction or amplification.
One disadvantage of the kind of arrangement just described is the relatively large profile height H, which is necessary because the wheels in wheel/pinion gearboxes have to be arranged at individually staggered positions. In addition, using non-uniform wheel/pinion pairs causes high tooling costs and increases the costs for parts inventory and assembly.
The object of the present invention is to avoid the drawbacks of the known gearboxes that are used to measure angles of rotation and to count numbers of revolutions and to develop a new gear-reduction device for measuring and transmitting rotary and swivel movements. Desired characteristics are that the device be suitable for integration into existing systems even under the severest installation constraints, for example in steering mechanisms of automobiles, and that the device be manufacturable with low tooling costs and an inventory of fewer different parts.
To meet the foregoing objective, the invention provides a gear-reduction device for measuring and transmitting rotary and swivel movements. The device has multiple wheel/pinion pairs, i.e., unitary elements in which a gear wheel and a pinion gear are rigidly mounted on a gear axle. When coupled to a rotary object whose angle of rotation is to be measured, the device produces at its output an amount of angular movement that is reduced in relation to the movement performed by the rotary object, whereby the measuring range is expanded. The device has a geometry where the gear wheels of different wheel/pinion pairs occupy different gear-wheel planes. The invention is advantageously distinguished in that at least a part of the gear-wheel planes are parallel to each other, but inclined at an oblique angle in relation to the plane of rotation of the rotary object. Furthermore in the inventive device, the wheels of the different wheel/pinion pairs are of equal diameter; the wheel/pinion pairs follow each other in a sequence where the pinion of each pair is engaged in the wheel of the next following pair; the wheel of the first pair in the sequence, i.e., the input wheel, is positively engaged and driven by the rotary object; and the pinion of the last pair or output pair, through a positive motion-transfer connection, controls the swivel movement of an optical angle-measuring device.
In one embodiment of the invention, the wheel plane of the input wheel is parallel to the plane of rotation of the rotary object.
In another embodiment, the wheel plane of the output pair is parallel to the swivel-motion plane of the optical angle-measuring device.
In a further embodiment, all wheel planes are parallel to each other and inclined in relation to the plane of rotation of the rotary object.
Also within the scope of the invention is an embodiment, where the input wheel is kinematically coupled to a driving unit and the output pair has a central output shaft transmitting movement to a driven device.
A further developed version of the preceding embodiment has a base plate and a cover plate. The driving shaft or input shaft and the driven shaft or output shaft of the device run in bearings mounted in the base plate and the cover plate; the gear-reduction device is flange-mounted on the driving unit and forms a unitary module with the driving unit.
The novel features that are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.